1. Field of the Invention
The present invention relates to a developing apparatus, and more particularly to the developing apparatus which provides a capability of preventing the inside and the outside of the developing apparatus itself from being contaminated by the developing powder when the exhausted developing powder is recovered from the developing apparatus in an electronic photography type copying machine and printer.
2. Description of the Related Art
The inventors of the present application know that the developing powder used in an image forming apparatus of an electronic photography type has been weary after several thousands to ten thousands of papers are developed. The worn-out developing powder causes the quality of the developed image to be degraded. And it may be splashed inside and outside of the apparatus, thereby contaminating the inside and the outside of the apparatus.
To overcome this shortcoming, it is necessary to exchange the worn-out or exhausted developing powder. As means for recovering the exhausted developing powder, the inventors know the traditionally proposed mechanisms described below.
As a first known mechanism, a recovery vessel is located in the circulating path of a developing bath so that the developing powder left in the bottom part of the developing bath may be recovered by means of a magnet. As a transformation of the first known mechanism, the magnet is arranged to travel as it is attracting the exhausted developing powder.
As a second known mechanism, a concave catch pan* is located in the lower part of the developing bath so that the developing powder may be received by the catch pan* and then is recovered into the recovery vessel.
As a third known mechanism, a shutter provided on the bottom of the developing bath is made open over the overall length of the circulating part of the developing powder. From the open shutter, the exhausted powder is recovered into a recovery vessel detachably mounted under the bottom of the developing bath.
The foregoing known mechanisms have the following disadvantages. The first known mechanism may cause the splash or the drop of the developing powder resulting from the rotation of a developing roller. The second known mechanism is arranged to temporarily receive the developing powder in the catch pan. When the powder drops into the catch pan, the powder may be splashed into the inside of the apparatus itself, thereby contaminating the inside of the apparatus itself. The third known mechanism needs a user to open the shutter horizontally by his or her hand when the exhausted powder is recovered. It means that this mechanism needs an additional troublesome operation. Further, the developing powder fitted to the shutter may drop around it. This results in contaminating the outside of the apparatus itself.